Process of producing a solid pentachloropropane



atented May 20, 1947 UNITED ST PROCESS OF PRODUCING A SOLIDPENTACHLOROPROPANE sylvanla No Drawing. Application May 27, 1943, SerialNo. 488,737

Claims. 1

The present invention relates to a process for the preparation of asolid pentachloropropane, and more particularly it relates to a processfor the production of 1,1,1,2,3,pentachloropropane (CHzCl-CHCl-CCla) bythe direct chlorination of l,l,l,2,tetrachloropropane (CHa-CHCl-CClz)This pentachloropropane is a. white crystalline solid, having the odorof camphor, and is soluble in organic solvents but insoluble in water.It is compatible with nitrocellulose and other plastics, and, as anintermediate, it can be dehalogenated, dehydrohalogenated, and enterinto other halide reactions, producing additional compounds. Heretofore,a solid pentachloropropane has not been available commercially, sincethe methods available for its preparation have been laborious,time-consuming, and expensive and have required special techniques andconditions of operation. These methods have involved the chlorination of3,3,3,trichloropropene-1 or the treatment of 1,l,1,trichloro 2bromopropane with antimony pentachloride (Beilstein, vol. I, p. 107).The starting material in both procedures is chloral, and this must beconverted into 3,3,3,trichloropropanol-2 by reaction of the chloral withdimethyl zinc or a methyl magnesium halide by the Grignard synthesisrequiring the use of absolute anhydrous ether. The preparation of the3,3,3,trichloropropanol-2 is illustrated by the following equations:

CCla CHO+ CHaMgI-i-HzO CC]: CHOH CHa-i-MgOI-II OI In the preparation ofthe pentachloropropane from 3,3,3,trichloropropenel, the3,3,3,trichloropropanol-2, prepared as above described, is dehydrated byphosphorus pentoxide to form the 3,3,3,trichloropropene-1, and thiscompound is then chlorinated. The following equations illustrate thesereactions:

In the preparation of the pentachloropropane from 1,1,1,trich1oro, 2bromopropane, the 3,3,3,trichloropropano1-2, obtained from chloral asabove described, is reacted with phosphorus trichloride, and theresulting chloro compound is treated with bromine to form the1,1,1,trichloro, 2 bromopropane, which in turn is reacted with antimonypentachloride to form 1,1,1,2,3,pentachloropropane, this series ofreactions are illustrated by the following equations:

CCIJ- CHOH-CHa-i-PClr CCla CHCl CHa-l-HPOCI:

CCI: 'CHCI CH3 +Brz- CCls CHBr CHs-i-BrCl The reactants required inthese procedures command high prices, and the combination of the expenseof the methods with the difilculties presented in handling the productsand the purification thereof prohibits the use of these processes on anindustrial scale. As an alternative to the involved methods described,attempts have been made to synthesize the pentachloropropane directlyfrom propane or propylene, but these attempts have resulted in liquidmixtures which are very difilcult to separate into the variouscomponents of the reaction, and have had no industrial significance.

One object of the present invention, therefore, is to provide a simple,direct, and eflicient process for the production of a solidpentachloropropane.

A further object of the invention is to provide a method by which1,1,1,2,3,pentachloropropane of high purity may be P pared in a singlesta chlorination and with a minimum of further processing.

Other objects will be apparent from a consideration of thisspecification and the claims.

In accordance with the process of the present invention, thepentachloropropane is formed by the chlorination of1,l,1,2,tetrachloropropane, either produced as an intermediate productin the reaction or employed as the starting material in the chlorinationprocess. Thus, the pentachloropropane may be formed by chlorinating1,1,1,2,tetrachloropropane or 1,l,dichloropropene- 1. If thedichloropropene-l is employed as the initial reactant, the chlorinesatisfies the double bond of the compound to form thetetrachloropropane, and. the further chlorination produces thepentachloropropane. Hence, the claims which are directed to the step ofchlorinating 1,1,1,2,tetrachloropropane cover the process broadly andinclude the use of 1,1,dichloropropene-l and 0f1,1,1,2,tetrachloropropane and of a mixture thereof as initial reactant.The reactions are illustrated by the following equations:

The 2,2,3,trlchlorobutanal-1 may be economically produced by the processof the copending appli cation of Ralph L. Brown and Ralph E. Plump,Serial No. 377,572, filed February 5, 1941, now Patent No. 2,351,000. Inmy copending application Serial No. 488,738 filed May 27, 1943;now

chlorinated until the chlorination is completed to form thepentachloropropane, and a moderate excess of chlorine over that requireddoes not deleteriously affect the product. The chlorine is brought intocontact with the material to be chlorinated under conditions favoringits absorption by the material treated. Hence, since the dispersion ofthe chlorine and its contact with the reacting liquid affects the extentto which it is v 10: utilized, active agitation and the use of adisperser, for example, a fritted glass disc or other type of dispersionplate or plates, has been found effective in the process. The rate ofgas passage into the reaction vessel is in general at least the maximumat which substantially complete utilization is obtained. Actually, thisrate is a complex function of temperature, catalyst, and design PatentNo. 2,370,577, a process is described by which 2,2.3.trichlorobutyricacid may be prepared by the chlorate oxidation of2,2,3.trichlorobutanal-l, and, if desired, the steam distillatefrom thepurification of the trichlorobutyric acid from the reaction mixture mayserve as the source of the material to be chlorinated. This steamdistillate usually contains some 1,1,1,2.tetrachloropropane and someunreacted 2,2,3,trichlorobutanal-1. and the latter compound may beconverted into 1,1,dichloropropehe-1 by treatment with alkalipsuch ascaustic soda. The material then may be dried, if desired, by the use ofcalcium chloride or other drying agent.

In accordance with the process of the present invention, the chlorine isbrought into contact with the 1,1,l,2,tetrachloropropane and/or the1,1,dihloropropene-l, and the pentachloropropane is produced by directchlorination. If 1,1,- dichloropropene-l or amlxture containing thissubstance is chlorinated, the material may be mixedwith a catalyst, forvexample, ferric chlo ride in an amount between about 0.05% and 0.5%based on the dichloropropene-l, and chlorine may then be broughtintocontact with the material at a. temperature between about" C. to 30 C.,

specifically in'the neighborhood of 20 C. while.

the material is agitated. This procedure will convert the1,1,dichloropropene-l into 1,1,1,2,- tetrachloropropane. Any otherprocedure may be followed in converting the 1,1,dichloropropene-1 intothe tetra-chloro compound and this step of conversion is not-in itself afeature of the present invention.

While in the chlorination of the 1,l,1,2,tetrachloropropan-e to form thesolid pentachloropropane, the reaction will take place without catalysis thereof, the reaction advantageously is catalyzed, since thechlorination then takes place at a faster rate, at a lower temperature,and in a more satisfactory and complete manner. The reaction may becatalyzed by actinic light. rays, such as sunlight, or ultraviolet rays,preferably the latter, or by the addition of a chlorination catalyst tothe material to be chlorinated. Examples of chlorination catalysts areferric chloride, antimony trior pentachloride, phosphorus pentachloride,chlorosulphonic acid, ferric oxide,-ferric sulphate, sulphur, iodine,red phosphorus, copper chloride, aluminum chloride, tetraethyl lead,stannic chloride, and the like. Of these, the ferric compounds, such asferric chloride, ferric sulphate, and ferric oxide, are preferred. Thecatalyst need onlybe present in a small quantity to be highly effective,for example, from about 0.05% to 05%, although larger amounts may beemployed, if desired. I V

'I'he chlorine is supplied to the material to be of the apparatus, butthe rate at which the chicrine is to be supplied may easily bedetermined in any particular instance. During the chlorination, anexcess of chlorine over that required at any instant byth'e reactionrate is advantageously available in order to minimize darkening of theproduct and to substantially eliminate side reactions. While the amountof excess chlorine need not be large, it is desirable that there be aready availability of chlorine for reaction at all times, say an excessof 1% to 10% over that reacting with the material to ,be chlorinated.The chlorine which escapes from the reacting vessel may, of course. berecirculated.

The chlorination may be conducted at any temperature at which thechlorination will proceed at the rate desired. The temperature employedin any particular case will be dependent upon whether or not a catalystis employed and the nature of the catalyst. For example, in a processwhere the reaction is catalyzed by ultraviolet light, the reaction willproceed at 25 C. or lower. Generally, however, temperatures above about65 C., and more specifically above C., willbe employed. The upper limitof the temperature will'also depend upon the presence or absence of acatalyst and the nature thereof, and the desired purity of the product,since it is possible to overchlorinate the material, which results in amaterial heavier than pentachloropropane. Advantageously, thetemperature employed, irrespective of the presence or absence of acatalyst and the nature thereof, will be between about 80 C. and 180 C.,temperatures within the range of from C. to 150 C., more specifically inthe neighborhood of C. to C., being particularly suitable in mostinstances.

The process is advantageously conducted at atmospheric pressure, but dueto the lower solubility of hydrochloric acid as compared to chlorine inthe reaction mixture, it may be advantageous to employ sub-atmosphericpressure. 0n the other hand, pressuresgreater than atmospheric pressuremay at times have a beneficial effect due to the increased solu'bilitypfth lchlorine in the reacting liquid, but, as stated, normally the use ofatmospheric pressure with adequate agitation is preferred.

Cther substances, such as water, may be present with the material to bechlorinated, and the presence of these materials may affect the rate ofchlorination, for example, it has been found that the presence of water,say from 1% to about 10% of water, decreases the rate of chlorination,but has the advantage of allowing the product to be separated in a;condition exceptionally free from contaminants, and of eliminatingcharring effects during the reaction.

Toward the end of the reaction, a solid material will form in thereaction mixture, if the reaction temperature is below the melting pointof the pentachloropropane in the presence of the other material. In anyevent, the pentachloropropane separates from the reaction mixture whenit is cooled. The pentachloropropane may be separated from the oilymaterial of the reaction mixture by any suitable means as by filtration,and the catalyst, if one was employed, may be removed by washing thesolid product with acidified water. The resulting solid product is atechnical grade of pentachloropropane, melting in the neighborhood of140 C. Yields of this technical grade of product of 80% or more areobtainable by the process of the present invention. Thispentachloropropane product may be purified by recrystallization from asolution of a suitable organic solvent such as ethanol. The pure gradehas a melting point not lower than about 178 C.

The reaction may be carried out in simple, nonspecialized equipment, andagitation may be furnished mechanically or merely by the incoming gas.The process of the present invention may be conducted as a batch processor as a semicontinuous or continuous process.

When 1,1,dichloropropene-1 or a mixture containing this substance ischlorinated, the chlorination may proceed Without interruption from the1,1,dichloropropene-1 through the 1,1,1,2,tetrachloropropane to thesolid pentachloropropane, with only such change in the temperatureconditions as may be necessary to obtain a satisfactory conversion ofthe tetrachloropropane to the pentachloropropane.

As pointed out above, the product of the procass is a solidpentachloropropane and although the process of the invention is not tobe limited to the production of a solid pentachloropropane of anyparticular molecular arrangement, identification tests of the productlead to the conclusion that the product is 1,1,1,2,3,pentachloropropane.These identification tests have included a comparison of the meltingpoint of the product with the melting point data in the literature forthe material obtained by other methods, and by molecular weight andchlorine determination. The product was also identified by a second anddifierent synthesis through chlorination of 3,3,3; trichloropropene-lprepared from 1,1,1,2,tetrachloropropane by dehydrohalidization withalcoholic potash. The properties of the pentachloropropane prepared inaccordance with this process of the invention resemble somewhat those ofhexachloroethane, and the product is generally similar to camphor in itsvapor pressure, melting point, odor, and waxy characteristics whencompressed.

The following examples are illustrative of the process of the presentinvention:

Example 1 Crude 1,1,1,2,tetrachloropropane (1084 gm.) (containing some1,1,dichloropropene-1), catalyzed by 1 gm. of anhydrous ferric chloride,was chlorinated (fritted glass disperser) in a flask fitted with refluxcondenser. The introduction of chlorine gas was begun at a temperatureof 105 C. and after ten minutes the temperature had risen to 120 C. anddarkening of the mixture occurred. The flask contents were cooled to 60C. at which point chlorination was continued for 1% hours. Thetemperature was then raised to 100 C. and the chlorination continued for6% hours. The total time of chlorination was 8 hours and 10 minutes, andsolid material had formed in the flask and condenser. On cooling, 1343gm. of slightly slushy solid was obtained, which was washed withacidified water to remove the ferric chloride and filtered with suction.The solid product obtained was pentachloropropane. A small quantity ofoil (D. 1.64, cc.) was separated by the filtration. In this example,substantially complete conversion of starting material to the desiredisomeric form of pentachloropropane was obtained.

Example 2 Crude 1,1.1,2,tetrachloropropane (360 gm.) (containing some1,1,dichloropropene-l), catalyzed by 1 gm. of anhydrous ferric chloride,was chlorinated for 30 minutes at C. and then at C.-130 C. for 3% hours.During the last 15 minutes, crystalline material formed in the reactionliquid and in the neck of the flask. A crude solid mass, weighing 440gm. was obtained on cooling. On pressing out on a suction funnel 40 cc.of an oil (D. 1.55) were separated. Two recrystallizations of the solidfrom alcohol gave material melting at 179 C., the recorded M. P. for1,1,1,2,3,pentachloropropane.

Example 3 1,1,1,2,tetrachloropropane (171 gm.) obtained by saturating1,1,dichloropropene-1 with chlorine below 45 C. to which 0.5 gm. offerric chloride and 5 cc. of water had been added, was chlorinated for 3hours at 9395 C. when 36 gm. of solid were separated on cooling. Thefiltrate was rechlorinated another 3 hours at 93-95 C. and 20 gm. ofsolid were separated. Finally, after 2 hours more of chlorination, thereaction product was distilled and that part distilling in the rangeISO-195 C. gave 16.5 gm. of solid pentachloropropane on good chilling.

Example 4 1,1,1,2,tetrachloropropane cc.) to which 12 cc. of water hadbeen added was chlorinated at the boiling point of the mixture for 10 /2hours. On cooling 77 gm. of solid pentachloropropane and 119 gm. liquidchloropropane were obtained.

Example 5 1,l,1,2,tetrachloropropane (26 gm.) catalyzed by 0.3-0.4 gm.chlorosulphonic acid was chlorinated with slowly rising temperature upto C. where the temperature was held for a short time, but after 35minutes from the start the temperature was raised to C. At thistemperature and after 2 hours (total time) the specific gravity of thereaction liquid rose to 1.55. The chlorination was then continued foranother hour (total 3 hours) after which an appreciable quantity ofsolid mass separated when chilled. This solid was pentachloropropane andupon a single recrystallization from ethanol had a melting point of174175 C.

Example 6 1,1,1,2,tetrachloropropane (24.7 gm.), catalyzed by 0.25 gm.antimony trichloride, was chlorinated at 150 C. for 3.75 hours and thenat 175 C. for 0.25 hour. The reaction product, on cooling and filteringave 16 gm. of crude pentachloropropane, which melted at 178 C. after asingle recrystallization from ethanol.

Example 7 1,1,1,2,tetrachloropropane (25.9 gm.), catalyzed camera by0.3.gm. phosphorus pentachloride, was chlorinated for 4'hours at 150 C.The reaction product now had a D4 of 1.54 and after good cooling asolid-crude product was separated which sintered at 140 C. and quicklyevaporated at about 184 C.

Example 8 A chlorination at 65 C. on 12.4v gm. of 1,1,1,2,-'

A chlorination at 80 C.-85 C. on about 10cc. of1,1,1,2,tetrachloropro-pane saturated with FeCla was carried out for 7.5hours. The reaction product was chilled and filtered and the crudepentachloropropane weighed about gm.

Example A chlorination was carried out on 5 cc. of 1,1,1,-2,tetrachloropropane exposed, at a distance of about twelve inches, tothe light of a 200 watt mercury vapor lamp. The reaction temperature wasat no time higher than 40 C. and was between 25 C.-40 C. After 1.6 hourstypical crystals appeared in the liquid, and after a totalreaction timeof 2.5 hours, the reaction product was chilled and filtered. This gave3.4 gm. of crude solid which, crystallized once from ethanol, melted at180 C.-181 C. with rapid evaporation. The density of the filtrate wasabout 1.56.

Example 11 Example 12 1,1,1,2,tetrachloropropane c. c.), catalyzed byabout'0.1 gm. F8203, was chlorinated at 100 C. for 2 hours. When thereaction product was cooled to about 25 C., the'entire batch becamesolid, and when it was pressed out on a suction filter only 1.5 cc. ofoil was obtained, indicating a high degree of conversion to solidpentachloropropane.

Erample 13 An uncatalyzed chlorination was carried out on 23.7 gm. of1,1,1,2,tetrachloropropane at its boiling point, which was about 154 C.After 2 hours, the D4, which initially was 1.49 at C., was found to be1.497. Chlorination for 3 hours more raised the density to 1.521. After3 hours longer chlorination, the density was found to be 1.540 and thetemperature of the boiling liquid was about 160 C. The chlorination wasagain resumed and in the next hour solid materialwas observed in thereflux condenser, but the treatment was continued for a final 2 hourperiod. The total reaction time was 11 hours, and the regm. of crudesolid pentachloropropane was obtained on cooling, and the D4 of thefiltrate was 1.56.

Considerable modification is possible in the conditions under which thechlorination is conducted, as well as in the choice of the catalyst ifone is employed, without departing from the essential features of thepresent invention.

The embodiment described herein, in which the chlorination oi 1,1,1,2,tetrachloropropane to form a solid pentachloropropane-containing productis catalyzed by actlnic light rays, is the subiect-matter of divisionalapplication Serial No. 738,929,1llecl April2, 1947.

I claim:

1. The steps of producing a solid pentachloropropane-containing productin which a solid pentachloropropane isomer having a melting point ofabout 180 C. predominates and from which said isomer may be separated,which comprises introducing chlorine into 1,1,1,2,tetrachloroprane at atemperature between about 65 C. and 180 C. until one hydrogen atom ofsaid tetrachloropropane is replaced by a. chlorine atom to produce saidpentachloropropane isomer, and thereafter recovering the solid productcontaining said solid pentachloropropane isomer from the reactionmixture.

2. The process of claim 1 wherein water is present with the1,1,1,2,tetraoh1oropropane.

3. The process of claim 1 wherein the temperature is between about C.and C.

4. The steps of'producing a solid pentachloropropane-containing productin which a solid pentachloropropane isomer having a melting point ofabout C. predominates and from which said isomer may be separated, whichcomprises introducing chlorine into 1,1,1,2,tetrachloropropane in thepresence of a chlorination catalyst at a temperature between about 65 C.and 180 C. until one hydrogen atom of said tetrachloropropane isreplaced by a chlorine atom to produce said pentachloropropane isomer,and thereafter recovering the solid product containing said solidpentachloropropane isomer from the reaction mixture.

5. The process of claim 4 wherein the catalyst is a ferric compound.

RALPH E. PLUMP.

REFERENCES CITED The following references are of record in the file ofthis patent:

' UNITED STATES PATENTS Number Name Date 1,306,760 Lacy July 8, 19191,362,355 Saunders et a1 Dec. 14, 1920 1,459,777 Lieser et al. June 26,1923 1,674,472 Jaeger June 19, 1928 2,147,577 Hass et a1 Feb. 14, 19392,174,737 Coleman et al Oct. 3, 1939 2,296,614 Hearne Sept. 22, 19422,323,227 Levine et a1 June 29, 1943 2,097,442 Cass Nov. 2, 1937 OTHERREFERENCES Beilstein, Handbuch der Organischen Chemie. vol. I, p. 107.

